摘要 |
Specific photochromic spirodihydrophenanthropyrans and their use in synthetic resin materials of all kinds, particularly for ophthalmic purposes. The compounds of the invention are photochromic pyran compounds derived from 9,10-dihydrophenanthrene in which at least one of the two carbon atoms at positions 9 and 10 belongs to a further ring system and thus forms a spiro linkage point.
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